Question

Mark can make 424242 birthday cakes in 777 days.

Answer 1

Mark can make 303,030 birthday cakes.
 

Answer 2

I think your quetsion was supposed to be
'Mark can make 42 birthday cakes in 7 days. How many birthday cakes can Mark make in 5 days?'

ratio and proprtion

cakes:days=42:7=42/7

42/7=x/5
42/7=x/5
6/1=x/5
times both sides by 5
30=x
30 cakes